Porous or foamed metal energy absorption device

ABSTRACT

The instant invention relates to a porous or foamed metal component which absorbs energy in an inelastic manner through curshing of the component by an external object. The instant invention in particular relates to a barrier such as a highway barrier, bridge barrier, or vehicle bumper wherein the porous or foamed metal component, and preferably a foamed aluminum component is operatively positioned so as to inelastically absorb energy upon impact.

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Peterson et a1.

1 1 Jan. 23, 1973 1 POROUS 0R FOAMED METAL 3,385,565 5 1968 Cuthbert ..256/13.1

ENERGY ABSORPTION DEVICE 1 1 3/ 1970 3,552,073 1/1971 [75] Inventors: Warren S. Peterson, Guilford', 3,552,698 1971 Clarence M. Tyler, Jr., New Haven, 3,536,502 2/1971 both of Conn.

, FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Olin Corp., New Haven, Conn.

1,534,481 7/1969 Germany ..256/13.1 1 Filed: J 1971 1,534,490 6/1969 Germany ..256/13.l 1,063,803 3/1967 Great Britain.. ..256/13.1 2 Appl' 156,447 432,573 9/1967 Switzerland ..256/13.l

[521 11.8. c1. ..256/l3.1, 52/98, 94/15, Primary Examiner-Dennis Taylor 293mm 3 25 Attorney-Robert H. Bachman et a1. [51] Int. Cl... ..1E0lf 15/00 [58] Field of Search ..256/13.1:1; 94/15; 52/98; 1 1 ABSTRACT 293/DIG- 3; 104/254 The instant invention relates to a porous or foamed metal component which absorbs energy in an inelastic 1 Relerences Cited manner through curshing of the component by an external object. The instant invention in particular re- UNITED STATES PATENTS lates to a barrier such as a highway barrier, bridge bar- 1,572,574 2 1926 Stromborg ..293/D1G. 3 ri r, r hi le mp r h in h p r r f m 2,089,929 10/1937 Brickman et a1. metal component, and preferably a foamed aluminum 2,121,379- 6/1938 Young ..256/l3.1 X component is operatively positioned so as to inelasti- 2,l55,651 4/1939 Goetzel ..'293/DIG. 3 ally absorb energy upon impact 3,214,265 '10/1965 Fiedler ..293/D1G. 3 3,381,427 5/1968 Watson ..52/98 5 Claims, 12 Drawing Figures PATENTEDmzsms 3,712,589

sum 1 [1F 4 4 H6 3 G WARREN s. PETERSON CLARENCE M. TYLL'R JR.

INVENTORS 4 I J Fwy/Ar I /z 1/ r r f 4 I ATTORNEJY PATENTEDJAH23 I915 3.712.589

SHEET 2 BF 4 WARREN S. PETERSON ATTORNEY PATENTEDJAH 23 1975 SHEET 3 BF 4 Q A n i 5 i? N WARRLW S. PETf/PSON CLARENCE M TVLERJR INVENTORS ATTORNEY PATENTEDJAN23 ms 3.712.589

sum 4 ur 4 PERCENT COMP/9E5 S/O/V H l2 WARREN 5 PETERSON CIA/ma 015% g w M ,10

ATTORNEY FOROUSOR FOAMED METAL ENERGY ABSORPTION DEVICE The present invention relates to a new and improved energy absorption device and in particular relates to new and improved highway barriers such as vehicle bumpers, highway guard rails, and highway bridge rails.

Various devices for energy absorption are well known such as springs and various pneumatic hydraulic devices wherein energy is substantially absorbed by these devices rather than for example a vehicle upon which they are mounted.

It is also well known that the increased number and speed of vehicles on highways has resulted in an increased amount of traffic fatalities and injuries.

Various devices such as guard rails, bridge rails and median barriers are generally employed in the highway system in order to prevent vehicles from leaving the roadway crossing a median divider strip into oncoming lanes of traffic. The type of barriers presently in use, however, although somewhat effective in holding an errant vehicle, may themselves cause injury to occupants of a vehicle due to the rigidity of the barrier and the resultant sudden deceleration, redirection or stopping of the moving vehicle. Naturally the more sudden the stop the greater the amount of damage to the vehicle and injury to the occupants since the occupants will continue forward at the same speed of the vehicle thereby resulting in a greater impact of the occupants with the interior of the vehicle. Should restraining devices such as seat belts be employed the occupant, although restricted from freedom of forward movement, would have a relatively large g-force applied which also increases the possibility of injury.

It is therefore particularly desirable to obtain a barrier wherein the rapidity of the stop is lessened and wherein a substantial portion of the energy resulting from the impact with the barrier is dissipated so that the rebound of the errant vehicle will not take it back so far into or towards the traffic lane.

Thus, it is a particular object of the present invention to provide a barrier wherein damage to the vehicle and risk of injury or fatality to occupants is substantially lessened. l

-It is a further object of the present invention to provide a barrier as aforesaid which is simple, convenient and relatively inexpensive.

Further objects and advantages of the present invention will appear hereinafter.

The energy absorption device and improved barrier of the present invention will be more readily apparent from a consideration of the drawings which form a part of the present specification wherein:

FIG. 1 is a perspective view of the energy absorber of the present invention before impact.

FIG. 2 is a perspective view of the energy absorber of the present invention after impact.

FIG. 3 is a side view of the barrier of the present invention when in the upright position before impacting with a moving vehicle.

FIG. 4 is a side view of the barrier of FIG. 3 after impact by a moving vehicle and subsequent deflection.

FIGS. 5 and 6 are side views of an alternative embodiment of the invention of FIGS. 3 and 4.

FIG. 7 is a perspective view of the vehicle bumper of the present invention.

FIGS. 8 and 9 are alternative embodiments of the invention of FIG. 7.

FIG. 10 is a side view of lighting pole of the present invention.

FIG. 11 is an alternative embodiment of the invention of FIG. Ml.

FIG. 12 shows the energy absorbing characteristics of the invention of FIG. 1.

The present invention comprises a porous metal component in an energy absorbing system which upon an impact at least a portion of the energy generated is absorbed in a substantially inelastic manner by the component. It is particularly preferred that the porous metal component is foamed metal and of aluminumor an alloy thereof.

As is readily seen in FIG. 1, voids 4 distributed throughout the matrix of the component 2 which allows the component to crush when impacted as shown in FIG. 2 and, therefore, absorb energy of the impact.

A skin covering 6, without voids, may be provided in order to more evenly distribute the energy impacted to the porous or foamed component if desired, although in many applications the skin 6 is not required since distribution of the energy may be afforded by other components of the barrier or moving vehicle into which the porous metal is incorporated.

As shown in FIG. 3, the porous or foamed metal, or alloy, component with aluminum and its alloys being preferred, is incorporated into a barrier so that upon impact with a moving vehicle the porous metal component absorbs a substantial amount of the energy created by the impact. The porous metal, or foamed aluminum component, is so positioned in such a barrier that the porous metal absorbs the aforesaid energy and is thereby crushed under the load. In being crushed the porous metal permits a substantial displacement under load of the structural members that deflect the errant vehicle. Such displacement in addition to the normal deflection of such structural members will substantially reduce the deceleration of the vehicle and hence reduce the g-forces that cause potential injury to the occupants of the vehicle.

FIG. 3 shows the barrier of the present invention in the upright position before impact. The porous metal component 2 is positioned beneath the upright post 8 and the concrete or cement base 6 of a bridge or a pedestal set in the soil along a highway. Longitudinal stringers 8 or a single stringer, extend between post 8 and additional posts placed along a bridge or roadway.

FIG. 4 shows the post 8 of FIG. 3 after having been impacted from a moving vehicle and after deflection of the post. It is clearly seen the post 8 is deflected away from the point of impact. It is also seen that the porous or foamed metal component 2 is crushed by the deflection of the post in a downward position since the post is deflected away and downward upon impact.

In this embodiment, the foamed or porous metal component beneath the post 8 is held in position by bolts 10 extending through plate 12 into a pedestal or concrete roadway 14. The plates are fastened to the post and when bolted into the roadway securely anchors the metal component beneath it. The plate also serves to distribute the crushing load impacted to the porous metal component which results in higher energy absorbing efficiency.

Naturally, various other suitable fastening means are readily apparent, such as riveting or forming the post and porous metal component as as integral unit.

As aforementioned, when highway barriers extend into the soil on each side of the roadway or in median strips in a divided highway type of system, a concrete block or other suitable pedestal may be set into the soil and then the post with the porous or foamed metal component beneath bolted, or in some other appropriate manner, fastened to the concrete block.

It is not particularly important in any of the aforementioned embodiments as to the exact means of holding the porous metal between the post and the concrete or pedestal 14 so long as sufficient rigidity is provided beneath the porous metal and the concrete or pedestal so that upon deflection the porous metal component such as aluminum and its alloys may be crushed.

FIG. 5 shows a second embodiment of the present invention whereby the porous or foamed metal component is placed between horizontal rails or stringers 16 and the post 8. In this manner deflection of the post 8 to crush the porous component 2 need not be relied upon since impact energy absorption will occur upon deflection of the rails 16 inward towards the post 8. Thus deflection of the post need not first occur in order to provide the required energy absorption. In this manner likewise any suitable fastening means to anchor the porous metal components into place between the rails 16 and the post 8 may be employed. For example, a single bolt as well as any other suitable attachment may anchor both the rail and the porous metal component to the post.

FIG. 6 is another embodiment of the present invention wherein the concept of both FIGS. 3 and 5 are employed. It is thus seen that components of porous or foamed metal, and most preferably aluminum and its alloys are positioned between both the rails 16 and the roadway or pedestal 14. This embodiment is particularly advantageous in the impacting of vehicles at higher speeds since two systems are employed thereby greatly increasing the energy absorption and lessening the deceleration of the impact;

By employing a porous or foamed metal component between the rails and the post crushing of the component not only directly served to absorb energy but also permits the rail 16 to deflect and spread the load on to adjacent posts. In addition, the impact energy applied by the moving vehicle to the barrier being substantially absorbed thereby increases the probability of the post not breaking thereby preventing the vehicle from leaving the roadway. Thus, for example, a bridge rail is less likely to break when an approach barrier tied thereto is struck by a vehicle, thereby preventing the vehicle from leaving the highway. Further, the rails are projected farther out from the post thus reducing the likelihood of the vehicle snagging on a post. This is particularly important in divided highway systems employing a median barrier wherein the vehicle could collide with an oncoming vehicle. Porous components placed solely beneath the post 8, as well as the combination of beneath the post and between the rails and the post, along a roadway also serve to enhance the probability of the post not breaking and causing the aforementioned results as is readily apparent.

An additional embodiment of the present invention is shown in FIG. 7. In this embodiment, at least one porous or foamed metal component 2 is suitably placed between the vehicle barrier or bumper 18 and chassis 20, and fastened by bolts or rivets 22, of a vehicle so that should the vehicle impact with a relatively stationary object much of the energy of impact will be absorbed by crushing of the porous metal.

FIGS. 8 and 9 depict alternative embodiments of the invention of FIG. 7. As shown in FIG. 8, a spring 24 may be employed in order to provide compression of the porous of foamed metal component to hold it in place between the bumper l8 and chassis 20. A bolt or rivet 26 fastened to the bumper extends through the spring and is fastened to the chassis in order to provide an anchor means and support for the spring.

Naturally, other suitable methods of providing foamed metal components between a bumper and vehicular chassis are contemplated. For example, a single large component 2 may be provided and suitably fastened in place such as by mount 28 as shown in FIG.

Naturally, also other suitable fastening means may also be provided since the method of fastening is not critical so long as the porous metal components are held in place at the strategic locations where the greatest amount of energy absorption will occur upon impact.

FIG. 10 shows still another embodiment of the present invention. In this embodiment a porous or foamed metal component is placed and suitably fastened beneath a rigid barrier such as a highway lighting pole 30 and in much the same manner as with guard rail barriers. In this arrangement, energy is likewise absorbed should an errant vehicle strike such a barrier upon leaving the travelled portion of the highway. Thus, the present invention is not limited to improved devices, the primary function of which is to prevent vehicles from leaving the highway, but also to other devices such as lighting poles, highway sign supports and the like.

FIG. 11 shows an improved embodiment of the standard type lighting pole. In this arrangement, a guard 32 is provided which serves to prevent damage to the pole 30 and also to lessen the possibility that the pole will snap with possible resultant additional damage to occupants of the vehicle or others upon the highway. Guard 32 is suitably fastened to plate 12 and the porous or foamed metal component such as by bolting or riveting. If desired, both the pole 30 and the guard 32 may be suitably fastened together or joined in a single integral component such as by casting.

The porous or foamed metal component of the present invention may be employed in a wide range of densities, pore sizes and in various alloys.

Aluminum and particularly its alloys are most preferred, as aforementioned. Although the specific aluminum alloy employed is not critical the aluminumcopper, aluminum-silicon, aluminum-magnesium, and the aluminum-manganese alloys are most preferred.

Likewise the particular densities and pore size of foamed aluminum and its alloys are not critical it is generally preferred that the density by with the range of 10-70 ft./lbs. and the pore size within the range of 1/32 in. to 3/16 in. As aforementioned aluminum and its alloys are most preferred and have excellent energy absorbing characteristics as well as tending to hold together when deformed.

Further, these components may be employed with or without a solid skin" surface rnetallurgically bonded to the foam. The ability of the foamed aluminum to absorb energy is naturally a function of these variables and these components may naturally be so designed for a particular application. Thus, the aforementioned properties are not in and of themselves critical and any foamed aluminum component within the meaning of this term is contemplated and suitable for the present invention. Thus, control of pore size, etc., are merely refinements and are not especially critical.

If desired, the pores of the porous or foamed metal may be coated with a suitable coating, such as a plastic, in order to minimize pick-up of contaminants such as salt and dirt which would therefore eliminate or reduce corrosion of the porous metal composite.

EXAMPLE FIG. 12 shows the Load-Deformationcharacteristics of foamed Al-l 0 Mg. alloy when tested under compression load. Samples tested were 1- /1. X 3- /8 inches and of a density of 38.9 lb./ft.

The data shown clearly indicates that the foamed aluminum functions as a highly efficient shock absorber, as the foamed aluminum is relatively soft under a small deformation and becomes progressively stiffer at an increasing rate as deformation proceeds.

This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be consider as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

What is claimed is:

I. A highway or bridge barrier comprising at least one longitudinal stringer and supporting posts for said stringer, said supporting posts being supported by support bases, said supporting posts being operatively positioned with respect to a highway and said at least one stringer being attached to said supporting posts foamed metal components operatively positioned intermediate said supporting posts and said support bases, said supporting posts being adapted to be deflected away and said foamed metal component adapted to be crushed under the load of an impacting vehicle, whereby said foamed metal component absorbs a substantial amount of the energy created by the impacting vehicle and said posts deflect under the load of the impact an amount greater than their normal deflection in the absense of said foamed metal component, said additional deflection of said posts substantially reducing the decelera tion of the vehicle and the g-forces that cause potential injury to occupants of the vehicle.

2. In the barrier of claim 1 further including means for fastening said foamed metal component to said post and to said support base.

3. In the barrier of claim 1 said foamed metal components being positioned between said stringers and said posts.

4. In the barrier of claim 3 further including means for fastening said foamed metal components to said stringers and to said posts.

5. In a barrier as in claim 4 wherein said foamed metal component is selected from the group consisting of aluminum and its alloys. 

2. In the barrier of claim 1 further including means for fastening said foamed metal component to said post and to said support base.
 3. In the barrier of claim 1 said foamed metal components being positioned between said stringers and said posts.
 4. In the barrier of claim 3 further including means for fastening said foamed metal components to said stringers and to said posts.
 5. In a barrier as in claim 4 wherein said foamed metal component is selected from the group consisting of aluminum and its alloys. 